QColumnView shows too much empty columns

Connect a QColumnView to a QDirModel.
Navigate down the directory structure some levels to a directory that contains both more sub directories and some files.
Select a directory.
Select a file.
Select a file at a higher directory level.
Perhaps you have to do this repeatedly.
Finally you will see an additional empty column (besides the preview widget).
This column may vanish and reappear when the mouse is moved accross it.